Adjustable speed-alternating-current motor



Jan.- 13. 1925. 1,522,742

' E. G. PARVIN ADJUSTABLE SPEED ALTEENATIQG CURRENT MOTOR' Filed Jan. 26, 1921 2 Sheets-Sheet l .lli

Jan.-13,1,925. 1,522,742

v E. G. PARVIN ADJUSTABLE SPEED ALTERNA'LING` CURRENT MOTOR INVENTOR 4 BY y 24522252 Patented Jan. 13, 1925. v I l i UNITED sTATEs PATENT OFFICE.

y EDWARD G. PARVIN, OFv ROSELLE, NEWJERSEY, ASSIGNOR TO ZOBELIr ELECTRIC MOTOR CORPORATION', 0F GARWOOD, NEW JERSEY, A CORPORATION OF NEW YORK.

ADJUSTABLE srnnnanrnimarmounannr Moron.

Application led January 26, 1921. Serial No. 439,921.

To all wilma t may cmwem: to the stator elements into the osition in 65 Be it known that I, EDWARD G. PARVIN, which some one rotor element isin posicitizen of the United States, and resident of tion for maximum magnetic interaction Roselle, in the countyvof Union and State of with a corresponding stator element, the

New Jersey, have invented certain new and magnetic interaction between each other eleuseful Improvements in Adjustable Speedmentand the corresponding stator elements 60 Alternating-Current Motors, of which the is'at less than its maximum value. The secfollowing is a specification. y ondary member of the motor may be ro- The general object Ofmy present invenvided with a simple squirrel cage win ing tion is to pro/vide a simple and'eiective ador windings or with distributed windings of justable speed alternating current motor various forms. Where the secondary com- 65 of the induction type'. In carrying out my prises a plurality of separately wound core invention I employ a primary motor mempartsthe windings on tlie different core ber(l1aving provisions for generating two parts may be separate from one another or 'p15 or more magnetic ,fields rotating at diiferin some cases the winding .of the secondary ont angular velocities about the motor axis, elements may be interconnected. 70 and make provisions for adjusting the pri- With whatever form of/,windings may be mary and secondary motor members axially employed, however, the windings on the difwith respect to one another, and so relaferent elements should be so'relatively artively arrange the p'rimary and secondary ranged that each rotor element when in its members of the motor, that by such axial position of maximum interaction with a 75 adjustment the inductive relation between corresponding staton element will tend to the windings of the secondary member and rotate at a speedg which is different the rotating fields induced by the primary 4from the speed at iwliich another rotor is varied in such manner that the speed of element tends to rotate when the latter is the rotor of the motor tends to be that of 'in fposition of maximum interaction with 80 one or another of the rotative speeds` of the corresponding stator.

- the magnetic fields -(less the necessary slip) For example, in a simple form of my or a mean of the speeds of rotation of difimproved motor comprising two rotors and 30.A ferent magnetic fields 'depending on the two stators, the latter being provided with axial adjustment. windings energized from the same multi- 85 The' primary member of the motor may phase current supply source, the stator be wholly a part of the 'rotor or wholly il. windings are arranged to make the poles part ofy the stator,\or the means for generatof one stator different inl number from the ing one of the primary magnetic fields may poles of. the other' stator so that the rebe carried by the rotor and the means for volving magnetic fields induced by the two generating the other rotary field or' fields stator elements will revolve at different 'may be carried by the stator; but in the velocities. lVith this form ofn my 4motor practical carrying out of my inventionethe rotor yelements will tend to revolve at 40 the primary-'member of the motor Ordinathe same speed (less the necessary slip), as

rily is a part of the stator, and the Secondthe field of one vstator element when the ary is carried by the rotor. The primary latter is in the position of maximum intermember must, in-general, comprise at least action with the corresponding rotor eletwo separate magnetic cores with the necesment' and when the rotor elements are 45. sary windings for generating the two magl axially adjusted to bring the other rotor .netic fields, and in practice I ordinarily into its position of maximum interaction 190 provide 'at least as many secondary core-with the other stator, the rotors will tend parts as there are primary core parts and to rotate at the speed of rotation (less the axially displace both the primary and .sec-A necessary slip) of the field of the .last menondary core parts, but the axial spacing tioned stator element. In intermediate axial apart of the primary element is different positions of the rotor elements, the rotors 10" from the axial spacing Aapart of the secwill revolve at intermediate speeds.

WMAfondary.nelements so that when the rotor In addition to the novel provisions reelement's are axially adjusted with respect ferred to for obtaining -a lvariation in the i Il motor speed by' an axial adjustment of the 4by it reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and de4 scribed some of the forms in which my invention may be embodied.

Of the drawings:

Fig. 1 is a, somewhat diagrammatic elevation in section of a motor having two stators and two rotors;

'Fig. 2 is a'diagram of windings and con nections employed in Fig.. 1;

Fig. 3 ,is a diagram of a modified wind-' ing arrangement which may 'be employed with the motor of Fig. 1;

Fig. 4 is a view taken similarly to\Fig. 1 illustrating a modification; and

Fig.v 5 is a diagram representing windings and connections which may be Lemployed with such a.motor as is shown in Fig. 4. j

The typical embodiment of my invention shown in Fig. 1 is al moto'r having two stator core ring elements B and b spaced apart from one anther and rigidly connected to the motor frame A'. The motor shaft G carries two rotor core elements E and e, which are spaced apart from one another and may be simultaneously adjusted axially with respect to the4 'stators As shown the rotor cores E and e4 are rigidly secured on a sleeve F which is splined on the motor shaft G, and may be axially adjusted'on the latter vby means of a collar or fork `member I workingin a groove F2 formed in the spidermemlger F and connected t0 a screw shaft J parallel to the motor shaft and' working in a threaded'aperture A formed in one `of the end members ofthe motor frame. The

shaft J is provided at itsouter end with a the sleeve F, and thereby the'rotors, may be axially adjusted back and forth between the positions shown in ull and in dotted lines .in Fig. 1. As shown, 'the' rotor elements E and e are spaced apartbya collar F', the axial length o which is such that when either of the 'rotor elements is centrally disposed with respect to the corresponding stator element, as the rotor element -E is and H? and H6; the adjacent windings being displaced from one -another by an angle disposed with respect to the stator element B in the full line showing ofFig. 1, the other rotor element is in the space between the adjacent sides of the two stators.

The windings orthe motor shown in Fig. 2 comprise two diametrically opposed field or primary windings D and I)3 for the stator B which are connected in series with one another between the supply conductors 1 and 3, and two intermediate windings D2 and D1 connected in series with one another between the supply conductor 2 and 4.V It will be understood that the supply conductors 1 and 3, 2. and 4 supply alternating currents displaced 90 in phase from one another. The windings for the stator b comprise four field windings d', d3, d5. and Z7 spaced at equal intervals around the axis of the stator and connected in series with the windings D and Ds between the supply conductors 1 and 3, and four windings d2, d, d6 and d8 intermediate the windings 0l', cl3, d5, Z7 respectively, and connected in series with the stator windings Dz and D* between the supply conductors 2 and 4. With this arrangement the stator B and b are wound for two and four poles respectively and the magnetic field' set up by the 4lield windings of the stator B will revolve with twice the velocit of the magnetic field setV up by the win ings 4for the stator b.

The windings shown in Fig. 2 for th rotor E comprise three pairs of diametrically opposed windings H and H4; H2 and H5;

of 60. The windingsl for the rotor e comprises six pairs of diametrically opposedcoils L, hf; 71.2, f1.8; 71.21112; h4, IL10; h5, 71,11; he, k12; eachwindingbeingangularly displaced-30 from its neighbors. The windings H 'and H4 of the rotor E are connected in serieswith the windings h', k7, 11.4, IL10 of the rotor e. Similarly the windingsH2 and H5 are. connected in series with the windings h2, hs, h5, h of therotor e, and the windings H3 and H arer connected in series with the windings ha, 4It", It, k12 of the rotor e. The windings on the rotors arethus three phase windings deltacon-A nected though. theymay be connected 1n Y, and the rotor e is wound for twice as many poles as the `rotor E.

In Fig. 3 I have illustrated, diagram-V matically, a motor which differs from thatshown in Figs. 1 and 2 in that the rotorsy EA and ea each has its own squirrel cage winding. l

With a supply currentV freuensly will cause a motor constructe an wound as shown in Figs. land 2, to revolve' with a speed of 3600 revolutions per minute when the rotor and stator elements arein the relative positions shown in full lines inFig. .1,

' X whichl l mediate of the maximum and minimum Y speeds of 3600 and 1800 revolutions per minute.

It is `hardly necessary to observe that with such a motor as is illustrated in Figs. 1 and 2 the'actual value of the maximum and minimum definite speeds depend upon the frequency of the supply current and the number of poles for whlch the different motor elements are wound, and that/oy a suitable relative arrangement of windings,

the minimum definite speed may be made more than or less than half the maximum definite speed. 7With such an embodiment 'of my invention as is illustrated in Figs. 1 and 2, thel motor has three lsynchronous speeds. One.

` of these is the motor speed when therotor 'E is wholly out of the influence ofthe stator B. Another is the speed when the rotor e is wholly out of the influence of the stator Y b. The. third synchronous speed is the inv termediate speed at which the flow through the windingsrof the rotor e of currents induced in the windings of the rotor E, vsets up a magnet-ic field which revolves in s'pace at the same speed as does the lield set 4up i by the windings of the stator element b. ,For

example, if the field set up by the windings of the two pole stator B revolves with a speed of 2000 revolutions per minute, and' the field set up by the four pole windings of the stator b revolves with a speed of 1000 revolutions per -minute, `the intermediate synchronous motor speeds will `be 13331/3 revolutions per minute.

The motor shown in Fig. 4 differs structurally from that shown in Fig. 1 in that its rotor comprises two additional unwound core elements EB and eb so spaced away from the rotor cores E and e,respectively, that vwith the rotor E in its position of maximum magnetic interaction /withthe stator B the rotor core element eb lies directly within the field o f the stator b, and when the rotor e lies directly within the field of the stator element b, the core element EB lies directly within thevlield of the stator B.

The windings for the rotor element E and e may be identical with those shown in Fig.

2 and this is true also of the two stator win ings except that, as` shown in Fig. 5, the

windings Afor the two stator elements are prefera ly connected parallel to the supply circuits since, the core elements eb and EB act inductivelyV to preventan unduew l-and 2 prevents an injurious rush of current through the windings of the stator B or statorl b due to their magnetic short circuitin so to speak, when the rotors are move into the positions for minimum or maximum speeds respectively.

While in accordance with the provisions of the' statutes I have illustrated and described the best forms of my invention now known to me, I Acontemplate the possibility of variations from the forms disclosed or suggested herein withoutv departin from the spirit of my invention as set fort 'in the appended claims, and those skilled in the art wi 1 understand that certain features of m invention may sometimes be used with a vantage without the corresponding use of Y other features.

Having now described my invention, what I claim as new and desirev to securevby Letters Patent, is:

1. An adjustable speed induction motor comprising coaxial primary and secondary members, provisions forI setting up in the primary member two axiall displaced magnetic fields rotating aroun the motor axis at diierent speeds, and provisions for adjusting the primary and secondary members axially with res ect to one another to thereby vary the re ative inductive effects of the two rotating fields on the secondary member of the motor.

2. In an induction motor, the combination with a rimary member inducing two axiall disp aced magnetic fields revolving with different angular velocities about the motor axis, of a secondary member comprising two interconnected, axially adjustable, polyhase windings, and means for axially adjusting the prlmary and secondary members' relative to each other t thereby vary the relative inductive eiects of the two rotating fields the' secondary member of the motor.

3. In an induction motor, the combination with a primary member inducing two axially displaced revolving magnetic elds, which revolve at dierent angular speeds, of a secondary member comprising core and winding parts so axiall an axial adjustment o the primary and secondary members relative to one another the inductive relation between one of said` elds and said secondaryv member may be made better orl worse depending upon the direction 'of the adjustment, while at the same time the inductive relation between the Aother field and the secondarymember is Union and State f New Jersey this twentyfourth day of January A. D. 1921.

disposed that by ,1125 .Signed at Garwood in the county of EDWARD G. QPARVIN.` 

